Piston



G. H. WOODWARD PISTON April 7,1925. 1,533,055

Filed May 17, 1922 Patented Apr. 7, 1925.

UNITED STATES GEORGE H WOODWABD, OF SAN FRANCISCO, CALIFORNIA.

PISTON.

Application filed May 17, 1922. Serial No. 561,602.

To all whom it may concern:

Be it known that I, GFDRGE H. WOOD- WARD, a citizen of the United States, residing at the city and county of San Francisco and State of California, have invented new and useful Improvements in Pistons, of which the following is a specification.

This invention relates to pistons, and especially to that type employed in internal combustion engines and the like.

For several years there has been a general tendency on the part of manufacturers of pistons for internal combustion engines to reduce Weight, or in other words produce a light Wei ht piston; this being desirable particula y in modern high speed motors as it materially reduces vibration, mechanical friction losses, bearing wear, etc. Today an almost universal demand forlight wei ht pistons has been created and due to t is demand extremes in design and weight reduction have been attempted to the point Where other necessary features have been lost. Cast-iron pistons have always been considered (preferable in motor design, but weight re uction to any considerable extent when this metal is employed has not been considered feasible. For this reason the general trend has been in the direction of substituting lighter metals, such as aluminum, alloys and the like, but these have proven more or less unsatisfactory, due to their'greater coefliciency of expansion, lesser tensile strength, etc.

The present invention embodies a castiron piston wherein light weight is attained without sacrificing strength and wearing qualities; the object of the invention being to generally improve and simplify pistons of this character; to reduce weight and especially to provide a series. of circumferenti ally and vertically disposed interior ribs whereby the thickness of the piston head, walls andskirt may be reduced to a minimum, and whereby the Wrist pin bosses will be reinforced and tied to the head, walls and skirt, thus producing a cast-iron piston which will retain its 'roundness and- One form whlch my invention may assume is exemplified in the following description and illustrated in the accompanying drawings, in which- Fig. 1 is a central, vertical, longitudinal section of the piston.

Fig; 2 is a side elevation taken at right angles to Fig. 1, said side elevation being partially in section.

Referring to the drawings in detail, A in? dicates in general a piston which is constructed of cast-iron. The piston is of the fiat head type and consists of a head member 2, a. skirt portion 3, wrist pin bosses 4, and an intermediate ring groove section 5, in which are formed the usual piston ring grooves 6. Formed interior of the piston and circumferentially thereof and at right angles to the longitudinal axis of the piston is a' series of superposed ribs 7,8, 9, and 10,

and disposed vertically within the piston is,

a pair of opposed ribs 11, one being in alignment with eachwrist pin boss. By referring to Fig. 1 it will be noted that the two upper circumferential ribs 9 and 10 are in alignment with the bosses 4, and are joined or in other words cast integral with the same as indicated at 12. Similarly, that the vertical ribs 11 extend from. the head to the bosses and as .such form an integral part thereof. In this manner a tie is formed'between the head and the bosses and to this extent forms a rigid support for the head and the bosses, and furthermore ties these parts together as an integral structure. It will also be seen that the'wrist pin bosses are further braced and supported by the circumferentially disposed I'lbS 9 and 10, and that a five-point support is'thus provided, four points of the support being indicated at 12, and the fifth support as at 14. 1

The circumferentially disposed ribs also form another function, t'o-wit, that of strengthening the skirt portion of the piston to the extent that it will retain the roundness of the same. It may be stated that these ribs form I-beam shaped braces interior of the piston which materially increases the strength thereof to resist external pressures which might have a tendency to distort the round formation of the piston, and they furthermore permit the formation of a skirt, the walls of which are exceedingly thin. The circumferentially disposed ribs therefore do not only aid in reinforcing and. supporting the wrist pin bosses 4, but they also reinforce the circumferential wall of the skirt, and they furthermore permit the thickness of said wall to be materially reduced and the final weight of the piston to be similarly reduced. In actual practice a circumferential skirt or wall having a thickness of approximately one-sixteenth of an inch has been found very satisfactory and as this portion of the piston represents the greatest weight, it can readily be seen that considerable weight reduction results therefrom, and 1 that wearing qualities and strength to withstand external and endwise pressure are in no way reduced as the essential parts of thepiston, to-wit, the wrist pin bosses and the head are tied and reinforced with relation to each other in such a'manner as to form an integral structure. p

In the larger type of pistons two circumferentially disposed ribs, such as indicated at 9 and 10, are preferably employed, While in smaller pistons a single centrally disposed rib may be emplo ed to advantage. I there- .-{Jiore wish it un erstood that one or more may be employed at this point, and similarly that other features of the design may be altered within the scope of the appended Iferentially disposed ribs formed on the inner face of the skirt and terminating in the wrist pin bosses at points adjacent their upper and lower sides, said ribs being horizontally disposed with relation to the longitudinal axis of the piston, and a pair of vertically disposed ribs, said ribs being cast integral with the piston head, the ring portion of the piston and the wrist pin bosses and extending inwardly into the piston a distance substantially equal to the length of the wrist'pin bosses, said vertical ribs and the horizontal ribs forming a five-point support for each wrist pin-boss.

GEORGE H. 

